1. Field of the Invention
The present invention relates to an ear-jack, and more particularly, to an ear-jack of a portable terminal capable of preventing the terminal from malfunctioning when a plug of an ear-phone is inserted into the ear-jack.
2. Description of the Background Art
FIG. 1 is a cross-sectional view showing an ear-jack in accordance with a background art, and FIG. 2 is a cross-sectional view showing a state that a plug of an ear-phone is completely inserted into the ear-jack of FIG. 1 according to the background art.
As shown in FIGS. 1 and 2, the ear-jack in accordance with the background art includes: a body 106 fixed to a portable terminal such as a mobile phone and having at the center portion thereof a passage 104 into which a plug 102 of an ear-phone can be inserted; and a plurality of connection terminals 130, 132, 134, 136 mounted on the body 106 and connected with the plug 102 when the plug 102 is inserted into the body 106, for transferring electrical signals of the portable terminal to the ear-phone or transferring electrical signals of the ear-phone to the portable terminal.
Mounting holes 108, 110, 112 and 114 installed to respectively allow the connection terminals 130, 132, 134, and 136 to be exposed to the inside of the passage 104 are formed at the passage 104 of the body 106. These mounting holes are formed at regular intervals in turn from an entrance of the passage 104 in the following order: the first mounting hole 108, the second mounting hole 110, the third mounting hole 112 and the fourth mounting hole 114. In addition, a plug detecting sensor 116 is installed at the body 106 such that the plug detecting sensor 116 detects whether or not the plug 102 is inserted into the body 106, and transfers signals to a CPU of the portable terminal when it detects that the plug 102 has been inserted into the body 106.
A first connection portion 120, a second connection portion 122, a third connection portion 124 and a fourth connection portion 126 are formed in turn at an outer circumferential surface of the plug 102 of the ear-phone at regular intervals, and a groove 128 is formed at the fourth connection portion 126. These connection portions are electrically insulated from each other, as indicated by shades. After the plug 102 of the ear-phone is inserted into the passage 104 of the body 106, one of the connection terminals (e.g., the connection terminal 136) elastically abuts against the groove 128, thereby preventing the plug 102 from coming out of the body 106.
The connection terminals includes: a ground terminal 130 elastically mounted at the body 106, disposed at the first mounting hole 108 and connected with the first connection portion 120 of the plug 102, for grounding the plug 102; a first speaker terminal 132 disposed at the second mounting hole 110 of the body 106 and connected with the second connection portion 122 of the plug 102, for transferring audio signals to the right speaker of the ear-phone; a second speaker terminal 134 disposed at the third mounting hole 112 of the body 106 and connected with the third connection portion 124 of the plug 102, for transferring audio signals to the left speaker of the ear-phone; and a microphone terminal 136 disposed at the fourth mounting hole 114 of the body 106 and connected with the fourth connection portion 126 of the plug 102, for transferring audio signals generated from the microphone of the ear-phone to the portable terminal such as the CPU of the portable terminal.
Here, when the plug 102 is not inserted into the body 106, the microphone terminal 136 is shorted to the plug detecting sensor 116 installed at the body 106 and therefore 0V (zero volt) is applied to the plug detecting sensor 116. Then, if the plug 102 is inserted into the body 106, the microphone terminal 136 is separated from the plug detecting sensor 116 and at this time the output voltage of the plug detecting sensor 116 increases to about 2.8V, thus supplying the CPU with signals indicating that the ear-phone has been electrically connected to the terminal.
In addition, when the plug 102 is completely inserted into the passage 104 of the body 106, the microphone terminal 136 elastically comes in contact with the groove 128 formed at the plug 102, thereby preventing the plug 102 from coming out of the passage 104 of the body 106.
An operation of the ear-jack of the portable terminal in accordance with the background art having such a construction will be described as follows.
Firstly, when the plug 102 of the ear-phone is not inserted into the passage 104 of the body 106, the microphone terminal 136 and the plug detecting sensor 116 are shorted to each other. Thus, the CPU recognizes that the ear-phone is not inserted into the portable terminal.
In such a state, when the plug 102 of the ear-phone is inserted into the passage 104 of the body 106, the first connection portion 120 and the ground terminal 130 are connected to each other, thereby grounding the plug 102. Then, the second connection portion 122 of the plug 102 and the first speaker terminal 132 are connected to each other such that audio signals generated from the portable terminal are transferred to the right speaker of the ear-phone. The third connection portion 124 of the plug 102 is connected with the second speaker terminal 134, thereby transferring audio signals generated from the portable terminal to the left speaker of the ear-phone. The fourth connection portion 126 of the plug 102 is connected with the microphone terminal 136, so that audio signals generated from the microphone of the ear-phone are transferred to the portable terminal.
At this time, as the microphone terminal 136 is separated from the plug detecting sensor 116 by means of the fourth connection portion of the plug 104, if a voltage of approximately 2.8V is generated at the plug detecting sensor 116 and electrical signals are transferred to the CPU of the portable terminal, the CPU recognizes that the ear-phone is inserted and connected to the portable terminal.
However, as shown in FIG. 3, in the ear-jack of the portable terminal having the construction and operation as discussed above, in the process of inserting the plug 102 of the ear-phone into the passage 104 of the body 106, the fourth connection portion 126 of the plug 102 first comes in contact with the microphone terminal 136 and as a result, the microphone terminal 136 is separated from the plug detecting sensor 116 in a state that the plug 102 is not completely inserted into the passage of the body 106. Thus, there is a problem that the portable terminal malfunctions may occur because signals indicating that the ear-phone has been inserted and connected to the portable terminal are supplied to the CPU of the portable terminal before the plug 102 is completely inserted in the passage 104 of the body 106.
In addition, in the process of inserting the plug 102 fully into the passage 104, the microphone terminal 136 and the second speaker terminal 134 come in contact with the fourth connection portion 126 of the plug 102 at the same time as shown in FIG. 3, and thus the microphone terminal 136 and the second speaker terminal 134 are shorted. Accordingly, a malfunction that a call is connected when the plug 102 is inserted into the passage of the body 106 occurs because the CPU of the portable terminal recognizes that a call button is pressed.